The disclosure relates to a rotation rate sensor, in particular for use in motor vehicles.
Micromechanical rotation rate sensors are used for detection of a current movement state in a wide range of technical fields, for example in driving stability systems in a motor vehicle, or else for navigation.
A rotation rate sensor such as this normally comprises a so-called spring-mass system having a substrate, which acts as a reference, and having a seismic mass, which is arranged such that it can move with respect to the substrate. A reaction of the seismic mass to a rotary movement is in this case used to detect the rotary movement. For example, in the case of a rotation rate sensor whose detection of the rotation rate is based on the Coriolis effect, the seismic mass is deflected at right angles to the rotation axis. The radial movement of the seismic mass results in a change in the rotating system to the path velocity thereof, which leads to a corresponding Coriolis force on the seismic mass. This Coriolis force can be measured as a tangential acceleration. If the characteristics of the rotation rate sensor are known, that is to say for example the mechanical characteristics of the spring-mass system, the current rotation velocity, and therefore the rotation rate, can be calculated from this.
In order to measure the Coriolis force, a defined movement of the seismic mass is first of all necessary. For this purpose, a periodic movement of the seismic mass is produced, for example, by means of a capacitive drive. This can likewise be used for detection of the Coriolis force. One such sensor has been disclosed, for example, in DE 10 2009 000 679 A1.
Therefore, overall, a movement of the seismic mass takes place both on the plane of the drive and at right angles to it, because of the Coriolis force. Undesirable oscillations occur in this case, caused by the drive. These undesirable oscillations are also detected as so-called quadrature signals, and corrupt the measurement results. One reason for these undesirable oscillations is, for example, deformations, asymmetries, etc. in the structure of the rotation rate sensor, caused by manufacturing tolerances during the production of the rotation rate sensor.
A change in the ambient temperature leads to deformations of the measurement structure within the rotation rate sensor. In consequence, the measurement sensitivity of the rotation rate sensor changes or drifts in some cases by up to 10%.
In order to produce a rotation rate sensor, it is therefore necessary to compensate for these deformations, for example by means of temperature curves.